From d2246a5bcf654fdefbd33a5cb2c6437f888e87e0 Mon Sep 17 00:00:00 2001
From: Karel Zak <kzak@redhat.com>
Date: Wed, 4 Jan 2023 18:34:03 +0100
Subject: [PATCH] include/cctype: add c_strcasecmp() and c_strncasecmp()

Sometimes, we need to compare ASCII-only strings independently on the
current locales. Let's follow our cctype.h to implement such functions.

Addresses: https://github.com/util-linux/util-linux/issues/1991
Signed-off-by: Karel Zak <kzak@redhat.com>
---
 include/cctype.h | 34 ++++++++++++++++++++++++++++++++++
 lib/strutils.c   | 26 +++++++++++++++++++++++++-
 2 files changed, 59 insertions(+), 1 deletion(-)

diff --git a/include/cctype.h b/include/cctype.h
index 6ab644c6e1..4181b12256 100644
--- a/include/cctype.h
+++ b/include/cctype.h
@@ -322,4 +322,38 @@ static inline int c_toupper (int c)
 	}
 }
 
+static inline int c_strncasecmp(const char *a, const char *b, size_t n)
+{
+	int res = 0;
+
+        for (; n > 0; a++, b++, n--) {
+		unsigned int x = (unsigned int) *a;
+		unsigned int y = (unsigned int) *b;
+
+		res = c_tolower(x) - c_tolower(y);
+                if (res)
+                        break;
+        }
+        return res;
+}
+
+static inline int c_strcasecmp(const char *a, const char *b)
+{
+	int res = 0;
+
+	if (a == b)
+		return 0;
+
+	for (; *a != '\0'; a++, b++) {
+		unsigned int x = (unsigned int) *a;
+		unsigned int y = (unsigned int) *b;
+
+		res = c_tolower(x) - c_tolower(y);
+		if (res)
+			break;
+	}
+
+	return res;
+}
+
 #endif /* UTIL_LINUX_CCTYPE_H */
diff --git a/lib/strutils.c b/lib/strutils.c
index db73c00fca..b35d059419 100644
--- a/lib/strutils.c
+++ b/lib/strutils.c
@@ -1208,6 +1208,9 @@ int ul_optstr_next(char **optstr, char **name, size_t *namesz,
 }
 
 #ifdef TEST_PROGRAM_STRUTILS
+
+#include "cctype.h"
+
 struct testS {
 	char *name;
 	char *value;
@@ -1308,6 +1311,23 @@ done:
 	return EXIT_SUCCESS;
 }
 
+static int test_strutils_cstrcasecmp(int argc, char *argv[])
+{
+	char *a, *b;
+
+	if (argc < 3)
+		return EXIT_FAILURE;
+
+	a = argv[1];
+	b = argv[2];
+
+	printf("cmp    '%s' '%s' = %d\n", a, b, strcasecmp(a, b));
+	printf("c_cmp  '%s' '%s' = %d\n", a, b, c_strcasecmp(a, b));
+	printf("c_ncmp '%s' '%s' = %d\n", a, b, c_strncasecmp(a, b, strlen(a)));
+
+	return EXIT_SUCCESS;
+}
+
 int main(int argc, char *argv[])
 {
 	if (argc == 3 && strcmp(argv[1], "--size") == 0) {
@@ -1323,10 +1343,13 @@ int main(int argc, char *argv[])
 		printf("%s\n", ul_stralnumcmp(argv[2], argv[3]) == 0 ?
 				"match" : "dismatch");
 		return EXIT_SUCCESS;
+
+	} else if (argc == 4 && strcmp(argv[1], "--cstrcasecmp") == 0) {
+		return test_strutils_cstrcasecmp(argc - 1, argv + 1);
+
 	} else if (argc == 3 && strcmp(argv[1], "--normalize") == 0) {
 		return test_strutils_normalize(argc - 1, argv + 1);
 
-
 	} else if (argc == 3 && strcmp(argv[1], "--strtos64") == 0) {
 		printf("'%s'-->%jd\n", argv[2], strtos64_or_err(argv[2], "strtos64 failed"));
 		return EXIT_SUCCESS;
@@ -1355,6 +1378,7 @@ int main(int argc, char *argv[])
 				"       %1$s --cmp-paths <path> <path>\n"
 				"       %1$s --strdup-member <str> <str>\n"
 				"       %1$s --stralnumcmp <str> <str>\n"
+				"       %1$s --cstrcasecmp <str> <str>\n"
 				"       %1$s --normalize <str>\n"
 				"       %1$s --strto{s,u}{16,32,64} <str>\n",
 				argv[0]);
-- 
2.47.2